[SeaBIOS] varlow/extrastack vs code

[Paolo Bonzini]

On 18/02/2017 04:45, Kevin O'Connor wrote:
> On Fri, Feb 17, 2017 at 02:12:57PM +0100, Paolo Bonzini wrote:
>> On 15/02/2017 18:35, Dr. David Alan Gilbert wrote:
>>> Yes it seems to.
>>> One worry is that if we ever fix the qemu triple-fault so it really
>>> does what you're describing and only resets the CPU, then I'm not
>>> sure your int3 is the right choice.
>>>
>>> The other question is whether that protected-mode exit switch
>>> works in practice on qemu; it's going to come back with a lot of it's
>>> devices reset.
>>
>> Right, keyboard reset (and port 92h reset) should be an INIT and not a
>> full system reset.  But that's also something that should be fixed, not
>> a quirk to rely on...
> 
> Could we rely on the pci reset mechanism (port 0xcf9)?

That's only 3-4 years old, but 0xcf9 followed by keyboard reset should
always work.

Paolo